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Clock syncrhonisation limits in a cluster?

We have a cluster of eight nodes, where clock synchronisation through ntpd has not been working well and clocks have been getting out of sync. I know the fix is to fix the clocks, we are on it.... but does anyone know what the absolute limits are for discrepancies in the system clocks, of nodes in a cluster?


  • Jim_KnicelyJim_Knicely - Select Field - Administrator
    edited March 2019

    According to the vnetperf optimization tool, it is recommended to keep the clock skew < 1 second.


    [dbadmin@SE-Sandbox-43-node1 ~]$ /opt/vertica/bin/vnetperf --hosts,, latency
    The maximum recommended rtt latency is 2 milliseconds. The ideal rtt latency is 200 microseconds or less. It is recommended that clock skew be kept to under 1 second.
    test              | date                    | node             | index | rtt latency (us)  | clock skew (us)
    latency           | 2019-03-07_11:31:15,76  |   | 0     | 50                | 1
    latency           | 2019-03-07_11:31:15,76  |   | 1     | 91                | -2179
    latency           | 2019-03-07_11:31:15,76  |   | 2     | 104               | 1148
    JSON results available at: ./results.2019-03-07_11:31:13,608.json


  • Thanks for this! Sorry, read it at the time and it was useful and then got caught up in other problems.

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